Wavelength Tunable Ho³⁺-Doped ZBLAN Fiber Lasers in the 1.2-μ m Wavelength Region

Wavelength tunability of continuous-wave holmium doped ZrF₄-BaF₂-LaF₃-AlF₃-NaF fiber lasers operating in the 1.2- μm wavelength region was investigated with a Littrow configuration. A wavelength tuning range of 1184-1198 nm was obtained from the fiber output port of the laser. The spectral width was measured to be around 0.02 nm over the entire tunable range and a maximum output power of 81.6 mW at 1192 nm was obtained at a pump power of 1.97 W. The wavelength tunable range was found to be limited by the transmission of the fiber-optic wavelength division multiplexer and coupler. A broader wavelength tuning range of 1177-1201 nm was obtained with a simpler fiber laser construction from the zero-order diffraction output of the bulk grating.